NURS 302 Pathophysiology Exam 1:
Comprehensive Questions & Answers
with Rationales
Question: A patient has a genetic disorder characterized by an abnormal
form of hemoglobin. What is the most likely underlying mechanism at the
cellular level?
Answer: A mutation in the DNA sequence that codes for the globin chains
of hemoglobin.
Rationale: A gene mutation is a permanent alteration in the DNA
sequence. This alteration can lead to the production of a structurally
abnormal protein, such as the abnormal hemoglobin S seen in sickle cell
disease. This is a classic example of a genetic defect manifesting at the
protein level.
Question: A patient is diagnosed with cystic fibrosis. Which transport
mechanism is primarily affected by this genetic disorder?
Answer: Ion transport across epithelial cell membranes.
Rationale: Cystic fibrosis is caused by a mutation in the CFTR gene, which
encodes for a chloride channel. This defect disrupts chloride and water
transport across epithelial cells, leading to the production of thick, viscous
secretions in the lungs, pancreas, and other organs.
Question: A patient has a condition where the cell membrane is unable to
maintain its resting membrane potential. Which ion's movement is most
directly responsible for this potential?
Answer: Potassium (K+).
,Rationale: The resting membrane potential is largely determined by the
concentration gradient of potassium ions (K+) and the membrane's
permeability to K+. The cell is more permeable to K+, which leaks out,
leaving the inside of the cell negative relative to the outside.
Question: A patient is admitted with severe vomiting. Which acid-base
imbalance is most likely to develop?
Answer: Metabolic alkalosis.
Rationale: Vomiting leads to the loss of gastric acid (hydrochloric acid, HCl)
which is rich in hydrogen ions (H+). The loss of H+ increases the pH of the
blood, resulting in metabolic alkalosis.
Question: A patient with renal failure is unable to excrete hydrogen ions.
What acid-base imbalance is most likely to occur?
Answer: Metabolic acidosis.
Rationale: The kidneys are the primary regulators of bicarbonate (HCO3-)
and excrete hydrogen ions (H+). In renal failure, the inability to excrete H+
and reabsorb HCO3- leads to an accumulation of acid in the body,
decreasing blood pH and causing metabolic acidosis.
Question: A patient is hyperventilating due to anxiety. Which acid-base
imbalance is most likely to result?
Answer: Respiratory alkalosis.
Rationale: Hyperventilation causes an excessive loss of carbon dioxide
(CO2) through the lungs. CO2 is an acid; its loss leads to a decrease in the
partial pressure of carbon dioxide (PaCO2), which increases blood pH,
causing respiratory alkalosis.
Question: A patient with chronic obstructive pulmonary disease (COPD)
has difficulty exhaling CO2. Which acid-base imbalance is expected?
Answer: Respiratory acidosis.
Rationale: Hypoventilation leads to a retention of carbon dioxide (CO2). As
,CO2 accumulates, it forms carbonic acid, decreasing blood pH. This is the
hallmark of respiratory acidosis, commonly seen in conditions that impair
ventilation, such as COPD.
Question: A patient is diagnosed with hyperkalemia. Which condition is a
potential cause of this electrolyte imbalance?
Answer: Adrenal insufficiency (Addison's disease).
Rationale: Aldosterone, released by the adrenal cortex, promotes the
excretion of potassium (K+) in the urine. In adrenal insufficiency, there is a
deficiency of aldosterone, leading to decreased K+ excretion and resultant
hyperkalemia.
Question: A patient is taking a loop diuretic. Which electrolyte imbalance is
a common adverse effect of this medication?
Answer: Hypokalemia.
Rationale: Loop diuretics, such as furosemide, act on the ascending loop of
Henle to inhibit sodium and chloride reabsorption. This also promotes the
loss of potassium (K+) in the urine, leading to hypokalemia.
Question: A patient with a history of alcoholism presents with confusion
and muscle twitching. A serum electrolyte panel reveals a low magnesium
level. Which electrolyte imbalance is most likely contributing to the
patient's neurological symptoms?
Answer: Hypomagnesemia.
Rationale: Magnesium is essential for proper neuromuscular function.
Hypomagnesemia, often seen in chronic alcoholism due to poor nutrition
and increased renal excretion, can cause neuromuscular irritability, tremors,
and confusion.
Question: A patient's arterial blood gas (ABG) results show a pH of 7.50,
PaCO2 of 30 mmHg, and HCO3- of 24 mEq/L. How would you classify this
acid-base disorder?
, Answer: Respiratory alkalosis, uncompensated.
Rationale: The pH is elevated (alkalemia). The PaCO2 is low, indicating a
respiratory cause (hyperventilation). The HCO3- is normal, meaning there is
no renal compensation yet. This is a classic example of uncompensated
respiratory alkalosis.
Question: A patient's ABG results are pH 7.30, PaCO2 50 mmHg, and
HCO3- 30 mEq/L. How would you classify this acid-base disorder?
Answer: Respiratory acidosis, partially compensated.
Rationale: The pH is low (acidemia). The PaCO2 is elevated, indicating a
respiratory cause (hypoventilation). The HCO3- is elevated, indicating the
kidneys are attempting to compensate by retaining bicarbonate. However,
the pH is still abnormal, indicating only partial compensation.
Question: A patient's ABG results are pH 7.48, PaCO2 43 mmHg, and
HCO3- 32 mEq/L. How would you classify this acid-base disorder?
Answer: Metabolic alkalosis, partially compensated.
Rationale: The pH is elevated (alkalemia). The HCO3- is elevated, indicating
a metabolic cause (e.g., vomiting or diuretic use). The PaCO2 is slightly
elevated, indicating the lungs are attempting to compensate by
hypoventilating (retaining CO2). The pH is still abnormal, so it's partial
compensation.
Question: A patient's ABG results are pH 7.32, PaCO2 37 mmHg, and
HCO3- 18 mEq/L. How would you classify this acid-base disorder?
Answer: Metabolic acidosis, partially compensated.
Rationale: The pH is low (acidemia). The HCO3- is low, indicating a
metabolic cause (e.g., renal failure, DKA). The PaCO2 is slightly low,
indicating the lungs are attempting to compensate by hyperventilating
(blowing off CO2). The pH is still abnormal, so it's partial compensation.
Comprehensive Questions & Answers
with Rationales
Question: A patient has a genetic disorder characterized by an abnormal
form of hemoglobin. What is the most likely underlying mechanism at the
cellular level?
Answer: A mutation in the DNA sequence that codes for the globin chains
of hemoglobin.
Rationale: A gene mutation is a permanent alteration in the DNA
sequence. This alteration can lead to the production of a structurally
abnormal protein, such as the abnormal hemoglobin S seen in sickle cell
disease. This is a classic example of a genetic defect manifesting at the
protein level.
Question: A patient is diagnosed with cystic fibrosis. Which transport
mechanism is primarily affected by this genetic disorder?
Answer: Ion transport across epithelial cell membranes.
Rationale: Cystic fibrosis is caused by a mutation in the CFTR gene, which
encodes for a chloride channel. This defect disrupts chloride and water
transport across epithelial cells, leading to the production of thick, viscous
secretions in the lungs, pancreas, and other organs.
Question: A patient has a condition where the cell membrane is unable to
maintain its resting membrane potential. Which ion's movement is most
directly responsible for this potential?
Answer: Potassium (K+).
,Rationale: The resting membrane potential is largely determined by the
concentration gradient of potassium ions (K+) and the membrane's
permeability to K+. The cell is more permeable to K+, which leaks out,
leaving the inside of the cell negative relative to the outside.
Question: A patient is admitted with severe vomiting. Which acid-base
imbalance is most likely to develop?
Answer: Metabolic alkalosis.
Rationale: Vomiting leads to the loss of gastric acid (hydrochloric acid, HCl)
which is rich in hydrogen ions (H+). The loss of H+ increases the pH of the
blood, resulting in metabolic alkalosis.
Question: A patient with renal failure is unable to excrete hydrogen ions.
What acid-base imbalance is most likely to occur?
Answer: Metabolic acidosis.
Rationale: The kidneys are the primary regulators of bicarbonate (HCO3-)
and excrete hydrogen ions (H+). In renal failure, the inability to excrete H+
and reabsorb HCO3- leads to an accumulation of acid in the body,
decreasing blood pH and causing metabolic acidosis.
Question: A patient is hyperventilating due to anxiety. Which acid-base
imbalance is most likely to result?
Answer: Respiratory alkalosis.
Rationale: Hyperventilation causes an excessive loss of carbon dioxide
(CO2) through the lungs. CO2 is an acid; its loss leads to a decrease in the
partial pressure of carbon dioxide (PaCO2), which increases blood pH,
causing respiratory alkalosis.
Question: A patient with chronic obstructive pulmonary disease (COPD)
has difficulty exhaling CO2. Which acid-base imbalance is expected?
Answer: Respiratory acidosis.
Rationale: Hypoventilation leads to a retention of carbon dioxide (CO2). As
,CO2 accumulates, it forms carbonic acid, decreasing blood pH. This is the
hallmark of respiratory acidosis, commonly seen in conditions that impair
ventilation, such as COPD.
Question: A patient is diagnosed with hyperkalemia. Which condition is a
potential cause of this electrolyte imbalance?
Answer: Adrenal insufficiency (Addison's disease).
Rationale: Aldosterone, released by the adrenal cortex, promotes the
excretion of potassium (K+) in the urine. In adrenal insufficiency, there is a
deficiency of aldosterone, leading to decreased K+ excretion and resultant
hyperkalemia.
Question: A patient is taking a loop diuretic. Which electrolyte imbalance is
a common adverse effect of this medication?
Answer: Hypokalemia.
Rationale: Loop diuretics, such as furosemide, act on the ascending loop of
Henle to inhibit sodium and chloride reabsorption. This also promotes the
loss of potassium (K+) in the urine, leading to hypokalemia.
Question: A patient with a history of alcoholism presents with confusion
and muscle twitching. A serum electrolyte panel reveals a low magnesium
level. Which electrolyte imbalance is most likely contributing to the
patient's neurological symptoms?
Answer: Hypomagnesemia.
Rationale: Magnesium is essential for proper neuromuscular function.
Hypomagnesemia, often seen in chronic alcoholism due to poor nutrition
and increased renal excretion, can cause neuromuscular irritability, tremors,
and confusion.
Question: A patient's arterial blood gas (ABG) results show a pH of 7.50,
PaCO2 of 30 mmHg, and HCO3- of 24 mEq/L. How would you classify this
acid-base disorder?
, Answer: Respiratory alkalosis, uncompensated.
Rationale: The pH is elevated (alkalemia). The PaCO2 is low, indicating a
respiratory cause (hyperventilation). The HCO3- is normal, meaning there is
no renal compensation yet. This is a classic example of uncompensated
respiratory alkalosis.
Question: A patient's ABG results are pH 7.30, PaCO2 50 mmHg, and
HCO3- 30 mEq/L. How would you classify this acid-base disorder?
Answer: Respiratory acidosis, partially compensated.
Rationale: The pH is low (acidemia). The PaCO2 is elevated, indicating a
respiratory cause (hypoventilation). The HCO3- is elevated, indicating the
kidneys are attempting to compensate by retaining bicarbonate. However,
the pH is still abnormal, indicating only partial compensation.
Question: A patient's ABG results are pH 7.48, PaCO2 43 mmHg, and
HCO3- 32 mEq/L. How would you classify this acid-base disorder?
Answer: Metabolic alkalosis, partially compensated.
Rationale: The pH is elevated (alkalemia). The HCO3- is elevated, indicating
a metabolic cause (e.g., vomiting or diuretic use). The PaCO2 is slightly
elevated, indicating the lungs are attempting to compensate by
hypoventilating (retaining CO2). The pH is still abnormal, so it's partial
compensation.
Question: A patient's ABG results are pH 7.32, PaCO2 37 mmHg, and
HCO3- 18 mEq/L. How would you classify this acid-base disorder?
Answer: Metabolic acidosis, partially compensated.
Rationale: The pH is low (acidemia). The HCO3- is low, indicating a
metabolic cause (e.g., renal failure, DKA). The PaCO2 is slightly low,
indicating the lungs are attempting to compensate by hyperventilating
(blowing off CO2). The pH is still abnormal, so it's partial compensation.
